A decanting centrifuge is commonly used for separating solid matter from a solids-laden liquid. For example, drilling mud with solids entrained therein must be effectively cleaned so that the drilling mud can be recycled. For another example, many manufacturing and food processing systems use vast quantities of water. In such systems, the water picks up solid waste matter which must be removed from the water before it can be discharged, whether it is into the environment or into storage. Decanter centrifuges have proved to be effective and efficient in carrying out this function of removing the solids from the recyclable liquid.
Generally, a decanter centrifuge comprises a cylindrical or frustoconical bowl rotating in one direction and at a particular although variable speed, and a screw conveyor rotating in the same direction but at a different speed. The difference in the speeds of the bowl and the screw conveyor is commonly known in the art as the differential speed.
In a well known decanting centrifuge structure, liquid which is to be clarified enters an inlet to the centrifuge where it is brought up to rotational speed around the interior surface of the bowl. Heavier elements, i.e. solids, are brought to the interior surface of the bowl by centrifugal force (furthest from the axis of rotation), while lighter elements, i.e. water or drilling fluid, remains closer to the axis of rotation of the centrifuge. The screw conveyor, rotating at a speed slightly slower than that of the bowl, conveys the solids toward a beach in a conical portion of the bowl.
No matter how well a piece of machinery is built, eventually it will wear out. Within a limited number of hours of high speed operation, a centrifuge likewise will require maintenance and eventually will have to be replaced because of worn parts. However, even with much of a centrifuge at the end of its useful life, major and costly portions of the centrifuge have substantial useful life remaining. This means that a large, expensive piece of machinery is often scrapped because only part of the machine is worn out.
Also, with improvements in technology, some machinery is replaced simply because, although major portions of the machines have useful lifetime left in them, when major overhaul is called for, it makes good economic sense to upgrade the machinery. Such full scale machinery replacement is often a major expenditure and is not undertaken lightly.
Thus, there remains a need for a method of retrofitting a centrifuge to extend the useful lifetime of the machine, while simultaneously upgrading the performance of the machine.